Registration Dossier
Registration Dossier
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EC number: 221-338-7 | CAS number: 3069-40-7
Endpoint summary
Administrative data
Description of key information
Additional information
No data are available for the submission substance, trimethoxy(octyl)silane (CAS 3069-40-7; EC No. 221-338-7). However, reliable test data are available for the read-across substances trichloro(2,4,4-trimethylpentyl)silane (CAS 18379-25-4; EC No. 242-262-0) and trichloro(phenyl)silane (CAS 98-13-5; EC No. 202-640-8). Both substances rapidly hydrolyse to substances that are analogous to the silanol hydrolysis product of the registered substance (see the ecotoxicological discussion). Reliable short-term toxicity test results are available for freshwater fish (Oncorhynchus mykiss) and algae (Pseudokirchneriella subcapitata). The relevant short-term values are:
Fish: (96 h) LC50 >100 mg/L, read across from trichloro(2,4,4-trimethylpentyl)silane (CAS 18379-25-4). This is equivalent to >78 mg/L when expressed in terms of the silanol hydrolysis product (2,4,4-trimethylpentyl)silanetriol.
Algae: (72 h) EC50 >100 mg/L and NOEC ≥100 mg/L, read across from trichloro(phenyl)silane (CAS 98-13-5). These are equivalent to >74 mg/L and ≥74 mg/L, respectively, when expressed in terms of the silanol hydrolysis product phenylsilanetriol.
No short-term data are available for toxicity to invertebrates. However, a 21-day NOEC of 32 mg/L has been determined for the effects of trichloro(2,4,4-trimethylpentyl)silane (CAS 18379-25-4) on mortality and reproduction of Daphnia magna. This is equivalent to 25 mg/L when expressed in terms of the silanol hydrolysis product (2,4,4-trimethylpentyl)silanetriol.
The very rapid hydrolysis of trichloro(2,4,4-trimethylpentyl)silane (CAS 18379-25-4) (half-life <1 minute at pH 7 and 25°C) means it is likely that the test organisms in each test were exposed primarily to the hydrolysis products, (2,4,4-trimethylpentyl)silanetriol and hydrochloric acid.
The very rapid hydrolysis of trichloro(phenyl)silane (CAS 98-13-5) (half-life <1 minute at pH 7 and 25°C) means it is likely that the test organisms in each test were exposed primarily to the hydrolysis products, phenylsilanetriol and hydrochloric acid.
An activated sludge respiration inhibition 3 hour EC50 value of >1000 mg/L and NOEC value of ≥1000 mg/L (loading rate) were determined in a reliable study, read-across from triethoxy(octyl)silane (CAS 2943-75-1).
Refer to IUCLID Section 6 endpoint summary (CSR Section 7.0) for further discussion of the approach to chemical safety assessment and justification for read across.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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